The field of the invention is alkylidene compounds and arylidene compounds and the present invention is particularly concerned with the production thereof.
Alkylidene and arylidene compounds are prepared by the Knoevenagel reaction by condensing a carbonyl component with CH-acidic methylene compounds, for instance acetaldehyde with malonic-acid diethylester. Illustratively, amines acting as catalysts are piperidine or alanine in the presence of acetic acid: ##STR1##
The state of the art of Knoevenagel condensation reactions is disclosed in ORGANIC REACTIONS, Vol. 15, pp. 204-597, as published by John Wiley and Sons, Inc. (1957), the disclosure of which is incorporated herein by reference. Pages 274-581 of this reference include a tabular survey of the known Knoevenagal condensation reactions.
A further compound obtained in the reaction of acetaldehyde with malonic acid diethylester is the dicarboxylated product as disclosed by Henecka in Houben-Weyl, Vol. 8, pp. 365-502 (1952).
To displace the equilibrium, it is recommended that reaction water be entrained out of circulation using such means as benzene, toluene or chloroform. Substantially basic catalysts such as sodium or potassium acetate cause disproportionate by-product formation due to telomerization as disclosed in the Journal of Organic Chemistry, Vol. 38, p. 1512 (1973).
By CH-acidic compound is meant: Aldehydes, ketones, acids, esters, nitriles and nitrocompounds with at least one hydrogen atom in .alpha.-position to the functional group.